1. Technical Field
The present invention relates to a recording apparatus capable of printing images on the entire surface of a recording sheet without a blank, and more particularly, to a recording apparatus capable of simplifying the structure of a sheet feed mechanism and reducing manufacturing costs.
2. Related Art
JP-A-2007-45577 discloses a recording apparatus capable of printing images on the entire surface of a recording sheet without a blank. The recording apparatus includes a first sheet feed unit that is provided on the upstream side in a direction in which the recording sheet is transported during printing and a second sheet feed unit that is provided on the downstream side in the transport direction. Each of the sheet feed units includes a sheet feed roller that can be rotated by the driving force of an LF motor, which is a driving source, and a pressure roller that can come into pressure contact with the sheet feed roller by the driving force of a CR motor, which also is a driving source. The recording sheet is pinched between the sheet feed roller and the pressure roller of each of the sheet feed units and is then transported by the rotation of the sheet feed rollers.
Each of the sheet feed units is provided with a pair of roller supporting members that rotatably support a rotating shaft of the pressure roller. A roller supporting portion that can rotatably support the rotating shaft of the pressure roller is formed at one end of each of the roller supporting members, and the other end of each of the roller supporting members is elastically urged by an elastic member.
In addition, a printing unit that prints a desired image on the recording sheet is provided between the first sheet feed unit and the second sheet feed unit. The printing unit includes a platen roller that is rotatably provided on the transport path of the recording sheet and a thermal head that can come into pressure contact with the platen roller by the driving force of a UD motor, which is a driving source.
A pressure release mechanism that can separate the pressure roller from the sheet feed roller is connected to the pressure roller of the first sheet feed unit. The pressure release mechanism includes a connection gear and a driving gear that is rotatably supported substantially at the center of the cam shaft and is engaged with the connection gear. When a connection shaft is rotated by the CR motor, which is a driving source, the cam shaft is rotated at a predetermined angle through the connection gear and the driving gear, and the roller supporting member is rotated about a rotation supporting portion provided in a printer body against the urging force of the elastic member. Then, the pressure roller is separated from the sheet feed roller by a predetermined distance.
As described above, in the sheet feed mechanism of the recording apparatus capable of printing images on the entire surface of a recording sheet without a blank, in order to adjust the contact of the pressure roller with the sheet feed roller at an arbitrary timing during recording in the printing unit, it is necessary to provide a CR motor for bringing the pressure roller into pressure contact with the sheet feed roller or separating the pressure roller from the sheet feed roller, as well as the UD motor for bringing the thermal head into pressure contact with the platen roller or separating (moving up) the thermal head from the platen roller and the LF motor for rotating the sheet feed roller forward or backward, which are provided in a general recording apparatus. If the UD motor also serves as the CR motor, it is necessary to increase the capacity of the UD motor since the UD motor does not have a sufficiently large capacity, which results in an increase in manufacturing costs.
These and other drawbacks exist.